For what it's worth, I also received this message from Goodyear after a personal info request about the ZL1 tires a few weeks ago...it seems to me to be a copy/paste from a standard tire-care literature. Possibly the "Proper Procedures for the storage of tires" bit they mention above.
Thanks for contacting our website.
The best place to store tires is in a clean, dry, sunless area away from
strong air currents. Even though the rubber used to make tires is
formulated to resist effects of sunlight, ozone and water, the life of a
tire can be extended if exposure of these elements is minimized during
Stack tires flat so that the bottom tire will maintain its shape
Wrap each tire with an opaque polyethylene covering to minimize the
effects of oxygen and ozone. Most Goodyear retailers have storage bags
made specifically for this purpose
If tires are being stored outdoors, they should be raised off the
If tires are being stored while mounted on rims, they should be inflated
to 10 psi
If they are put in storage during warm weather, the initial inflation
pressure should be about 15 psi to offset the pressure drop during cold
How Not To Store Your Tires
Don't store tires in an area that is wet, oily or greasy
Don't store tires where they are subject to direct sunlight or extreme
Don't store tires near electric motors or other ozone-generating sources
Don't store tires on black asphalt or other heat-absorbent surfaces
Don't store tires on or adjacent to highly reflective surfaces such as
sand or snow
If you plan on storing your tires on the vehicle, we recommend inflating
the tires to the maximum inflation stated on the sidewall of the tire,
and moving the vehicle a few inches every couple of weeks ( to change
the footprint)so that it doesn't develop flat spots.
I don't foresee a huge issue. The lacerations, imo, would only be caused by extreme amounts of heating/cooling cycles during the few truly arctic weeks of winter, probably coupled with dry air, ozone, etc....they look tortured, not made of glass, imo.
Based on all this info...I'll store it somewhere dry (ie, not outdoors), and inflate them to max pressure. Roll the car 1/8 wheel-turn every month until the snow melts.